Method of Fault Locating

8/11/2019 Method of Fault Locating

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Huawei Transport Network MaintenanceReference (Volume 5)

RTN Microwave

Issue 01

Date 2011-12-30

HUAWEI TECHNOLOGIES CO., LTD.


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Huawei Transport Network Maintenance Reference

(Volume 5)

RTN Microwave About This Document

Issue 01 (2011-12-30) Huawei Proprietary and Confidential

Copyright Huawei Technologies Co., Ltd.

i

About This Document

OverviewFor assisting maintenance engineers in troubleshooting, this document describes how totroubleshoot OptiX RTN products, and is organized as follows:

Basic principles and common methods for locating faultsThis chapter describes basic principles and common methods for locating faults. Eachmethod is illustrated using an example.

Troubleshooting process and guide

This chapter describes the general troubleshooting process, fault categories, and how todiagnose each category of faults.

Equipment interworking guide

This chapter provides criteria for correct interworking between OptiX RTN products and

other products, and methods used for locating interworking faults.

Typical cases

This chapter provides typical troubleshooting cases for helping maintenance personnelimprove their fault diagnosis capabilities.

Appendix

This chapter provides references.

Intended AudienceThis document is intended for:

Technical support engineers

Maintenance engineers

Symbol ConventionsThe symbols that may be found in this document are defined as follows.

Symbol Description

Indicates a hazard with a high level of risk, which if notavoided, will result in death or serious injury.


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Symbol Description

Indicates a hazard with a medium or low level of risk, which ifnot avoided, could result in minor or moderate injury.

Indicates a potentially hazardous situation, which if not

avoided, could result in equipment damage, data loss,

performance degradation, or unexpected results.

Indicates a tip that may help you solve a problem or save time.

Provides additional information to emphasize or supplement

important points of the main text.

General Conventions

The general conventions that may be found in this document are defined as follows.

Convention Description

Times New Roman Normal paragraphs are in Times New Roman.

Boldface Names of f iles, directories, folders, and users are inboldface. For example, log in as user root.

Italic Book titles are in italics.

Courier New Examples of information displayed on the screen are in

Courier New.

Change HistoryUpdates between document issues are cumulative. Therefore, the latest document issue

contains all updates made in previous issues.

Updates in Issue 01 (2011-12-30)

This issue is the first formal release.


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Contents

About This Document ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... . i

1 Basic Principles and Common Methods for Locating Faults.......... .... .... .... .... .... ....... .... . 1

1.1 Basic Principles for Locating Faults ................. .......... ......... .......... .......... ......... .......... ........... .......... ......... 1

1.2 Common Methods for Locating Faults .......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .... 2

1.3 Signal Flow Analysis .............................................................................................................................. 3

1.3.1 Application Scenarios..................................................................................................................... 3

1.3.2 Method Description........................................................................................................................ 3

1.3.3 Application Example ................... .......... ......... .......... .......... ......... .......... .......... ......... .......... .......... .. 3

1.4 Alarm and Performance Analysis .... ........... .......... ......... .......... .......... .......... .......... .......... .......... ......... ...... 4




1.5 Receive and Transmit Power Analysis ................. .......... ......... .......... .......... ......... .......... ........... .......... ...... 6




1.6 Loopback ............................................................................................................................................... 7




1.7 Replacement......................................................................................................................................... 10

1.7.1 Application Scenarios...... .......... .......... ......... .......... .......... ......... .......... .......... .......... ......... .......... .. 10

1.7.2 Method Description...................................................................................................................... 10

1.7.3 Application Example ................. .......... ......... .......... .......... ......... .......... .......... .......... ......... .......... .. 11

1.8 Configuration Data Analysis .......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .......... ....... 12




1.9 Tests Using Instruments and Tools .... .......... .......... ......... .......... .......... .......... ......... .......... ........... ........ .... 13





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1.10 RMON Performance Analysis......... .......... .......... ......... .......... .......... ......... .......... .......... ......... ........... ... 15

1.10.1 Application Scenarios ......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .......... ....... 15

1.10.2 Method Description.................................................................................................................... 15

1.10.3 Application Example ................. .......... ......... .......... .......... ......... .......... .......... .......... ......... .......... 16

1.11 Network Planning Analysis.......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .......... ....... 17

1.11.1 Application Scenarios ......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .......... ....... 17

1.11.2 Method Description .......... .......... .......... ......... .......... ........... ......... .......... .......... ......... .......... ........ 17

1.11.3 Application Example ........ .......... ........... ........ ........... .......... ......... .......... .......... ......... .......... ........ 18

2 Troubleshooting Process and Guide ............................................................................ 21

2.1 Troubleshooting Process Overview .......... .......... .......... ......... .......... .......... ......... .......... .......... ......... ....... 21

2.2 Fault Categories.................................................................................................................................... 23

2.3 Troubleshooting Radio Links...... .......... .......... ......... .......... .......... ......... .......... .......... .......... ......... .......... 23

2.3.1 Radio Link Faults......................................................................................................................... 23

2.3.2 Signal Propagation Faults .......... .......... .......... ......... .......... .......... ......... .......... .......... ......... .......... .. 26

2.4 Troubleshooting TDM Services ............... .......... ......... .......... .......... .......... ......... .......... .......... ......... ....... 27

2.5 Troubleshooting Data Services ...... .......... .......... ......... .......... .......... ......... .......... .......... .......... ......... ....... 28

2.5.1 Services at All Base Stations on an Entire Network or in an Area Are Interrupted.... ............ ........ ..... 28

2.5.2 Services at All Base Stations on an Entire Network or in an Area Experience Packet Loss ................ 30

2.5.3 Services at Some Base Stations in an Area Are Interrupted ............................................................. 32

2.5.4 Services at Some Base Stations in an Area Experience Packet Loss ........ ............ ........ .... ............ ..... 35

2.6 Troubleshooting Microwave Protection ................. .......... ......... .......... .......... ......... .......... .......... .......... ... 37

2.6.1 Switchover Failure or Delay in Microwave 1+1 Protection ............................................................. 37

2.6.2 Failure to Switch to the Main Unit in Microwave 1+1 Protection ........ ........ ............ .... ........ ............ 38

2.6.3 Switchover Failure or Delay in SNCP Protection ... .......... .......... ......... .......... .......... .......... ......... .... 38

2.7 Troubleshooting Clocks......................................................................................................................... 39

2.7.1 Analyzing Clock Faults ...... .......... .......... ......... .......... ........... ........ ........... .......... .......... ......... ........ 39

2.7.2 Handling Common Clock Alarms ......... .......... .......... ......... .......... .......... ......... ........... .......... ......... 40

2.8 Troubleshooting DCN Communication .......... .......... .......... ......... .......... ........... ........ ........... .......... ......... 42

2.8.1 Fault Symptoms and Possible Causes ......... .......... .......... ......... .......... .......... ......... .......... .......... ..... 42

2.8.2 DCN Troubleshooting Process ......... .......... .......... ......... .......... .......... ......... ........... .......... ......... ..... 45

3 Equipment Interworking Guide ........ ........ ........ ........ ........ ........ ........ ........ ......... ........ .. 48

3.1 Interworking Criteria ............................................................................................................................ 48

3.1.1 Interworking Through Ethernet Ports ........... .......... .......... ......... .......... .......... ......... .......... .......... ... 48

3.1.2 Interworking Through SDH Ports.......... .......... .......... ......... .......... ........... ........ ........... .......... ......... 49

3.1.3 Interworking Through PDH Ports.......... .......... .......... ......... .......... ........... ........ ........... .......... ......... 50

3.2 Methods for Locating Interworking Faults... .......... .......... ......... .......... .......... .......... ......... .......... .......... ... 51

4 Typical Cases ................................................................................................................ 52

4.1 List of Cases......................................................................................................................................... 52

4.2 Radio Link Faults ................................................................................................................................. 53

4.2.1 Radio Link Interruptions Due to Multipath Fading ......................................................................... 53

4.2.2 Service Bit Errors Due to Interference to Radio Links .................................................................... 54


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1 Basic Principles and Common Methodsfor Locating Faults

This chapter describes basic principles and common methods for locating faults. Each method

is illustrated using an example.

1.1 Basic Principles for Locating Faults

Purpose

To locate a fault to a radio site or a radio hop.

Description

Fault locating aims to narrow down the most likely areas for faults, since transmissionequipment faults affect services in a large area.

Table 1-1 lists the basic principles for locating faults. These principles are summarized based

on characteristics of transmission equipment.

Table 1-1Basic principles for locating faults

Basic Principle Description

External first, transmission

next

Rule out external faults, for example, faults on power

supply equipment or interconnected equipment, or cable

damage.

Network first, NE next Locate a fault to a radio site or a radio based on fa ult

symptoms.

High-speed section first,low-speed section next

Alarms of high-speed signals generally cause alarms oflow-speed signals. Therefore, clear faults in the high-speed

section first.

High-severity alarms first,

low-severity alarms next

First handle high-severity alarms, such as critical alarms

and major alarms. Then handle low-severity alarms, suchas minor alarms and warnings.


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1.2 Common Methods for Locating FaultsTable 1-2 lists common methods for locating faults. Network faults can be located quickly byusing a combination of these methods. In actual applications, maintenance engineers areexpected to locate and rectify faults quickly by using various fault locating methods.

Figure 1-1Common methods for locating faults

Table 1-2Common methods for locating faults

Method

Applicable Scope

Brief Introduction

Signal flow analysis All scenarios This method helps locate a fault to a radio site or radio

hop. Familiarity with service signal flows, cable

connections, and air-interface link connections helpsanalyze fault symptoms and locate possibly faulty points.

Alarm analysis All scenarios Alarms well illustrate fault information. Handle alarms

reported by faulty points immediately after analyzing

service signal flows.

Receive and transmit

power analysis

Locating radio link

faults

By analyzing the current and historical receive and

transmit power on a radio link, determine whether any

errors, for example, interference and fading, exist on theradio link.

Loopback Locating a fault to a

component or site

section by section

This method is fast and independent of alarm and

performance event analysis. It , however, affects embedded

control channels (ECCs) and normal service running.

Replacement Locating a fault to a

component or board,

or identifying

external faults

This method does not require sound theoretical knowledge

or skills but requires spare parts. It applies to nearly sites.


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Method

Applicable Scope

Brief Introduction

Configuration dataanalysis

Locating servicefaults when both

hardware and radio

links work normally

This method covers configuration data analysis,configuration data modification, and modification

verification, and therefore has high requirements for

maintenance personnel.

Tests using instrumentsand tools

Isolating externalfaults and addressing

interworking issues

This method provides accurate results. Before using thismethod, interrupt services.

RMON performanceanalysis

Locating faults indata services

Statistics are collected routinely to analyze Ethernet boardinformation, for example, service performance.

Network planning analysis Diagnosing

performance

deterioration andfrequent interruption

of radio links

This method addresses availability issues of radio links. It

requires analysis of planned parameters such as fading

margin and of measures against multipath fading.

Experience-based fault

handling

Special scenarios With rich troubleshooting experience, you can locate

faults quickly by analyzing fault symptoms and networkarchitecture.

1.3 Signal Flow Analysis

1.3.1 Application ScenariosSignal flow analysis is commonly used to locate faults. It helps much in scenarios where

multiple network elements (NEs) become unreachable to the network management system(NMS) or multiple points are faulty in base station services.

1.3.2 Method Description

Based on network connection diagrams, logical service relationships, and system functional

block diagrams, this method allows you to analyze service f low directions to obtain possibly

faulty points and locate those faulty ones.

Use this method if you need to locate a fault to a site or link on a network or locate a fault to amodule.

1.3.3 Application Example

Fault Symptoms

As shown inFigure 1-2,a microwave chain network was set up, and all 2G and 3G basestation services in an area were interrupted for approximate ly 10 minutes.


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Figure 1-2Network example for signal flow analysis

Area where services were interrupted

Backhaul signal flow

NE1701NE1702NE1703

NE1704

NE1709NE1710NE1711NE1712

NE1708 NE1707 NE1706 NE1705

Cause Analysis and Handling Procedure

Step 1 Checked the distribution of the NEs on which services were interrupted and the service flowdirection.

NE1704 converged the interrupted services, so the service interruption was related to

NE1704.

Step 2 Checked alarms and operation records on NE1704.

NE1704 reported an MW_CFG_MISMATCH a larm, and the Hybrid radio E1 capacity was

changed on NE1704 right before the services were interrupted. It was inferred that theservices were interrupted due to an E1 capacity mismatch between NE1704 and NE1705.

Step 3 Corrected the Hybrid radio E1 capacity on NE1704.

The fault was rectified.

----End

Conclusions and Suggestions

If services are interrupted at multiple points, signal flow analysis generally proves that their

convergence point is faulty.

1.4 Alarm and Performance Analysis

1.4.1 Application Scenarios

Alarms well illustrate fault information. When a fault occurs, first check the alarms reported

by possibly faulty equipment.

Checking current and historical alarms, fault symptoms, and fault time helps narrow down the

most likely areas for faults, and helps locate a fault to a hop, site, or module.


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The alarm and performance analysis method entails capabilities in using the NMS and

analyzing service signal flows.


Step 1 Use the NMS to obtain information about equipment alarms and performance events on anentire network.

Step 2 Sort the alarms by severity and handle the alarms in the following sequence:

1. Hardware alarms, such as HARD_BAD, BD_STATUS, and VOLT_LOS

2. Link alarms, such as IF_CABLE_OPEN, MW_LOF, RADIO_RSL_LOW, R_LOC,

R_LOF, and R_LOS

3. Service alarms

4. Protection alarms, such as HSB_INDI, RPS_INDI, XCP_INDI, and APS_INDI

----End


Fault Symptoms

An OptiX RTN 620 NE on a network reported a HARD_BAD alarm and an XCP_INDIalarm.


Step 1 Checked a larms.

Boards in slots 1, 5, 6, and 7 reported the HARD_BAD alarm.

The PXC board in slot 1 reported a HARD_BAD alarm, whose parameters indicated that

the 38M clock was lost and the analog phase-locked loop (PLL) was unlocked.

The boards in slots 5, 6, and 7 reported the HARD_BAD alarm, whose parameters

indicated that the 38M clock was lost and the PXC board in slot 1 was faulty. The faultcaused loss of the first 38M clock.

Step 2 Checked the XCP_INDI alarm.

The HARD_BAD alarm reported by the board in slot 1 triggered a switchover, causing theSCC board to report an XCP_INDI alarm.

Step 3 Replaced the PXC board in slot 1.

The alarms cleared.

----End


If an NE simultaneously reports multiple alarms, analyze their severities, correlations, and

parameters so you can quickly locate the fault to a board or port.


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1.5 Receive and Transmit Power Analysis


Receive and transmit power analysis is crucial to radio link analysis. This method allows youto determine whether any faults, for example, radio link blocking, fading, and outdoor unit

(ODU) faults, occur on a link by analyzing current and historical receive and transmit poweron the link, thereby quickly locating the fault.


This method allows you to check the receive and transmit power on a link, as well as their

changes using the NMS.

By periodically updating the receive and transmit power table based on radio link directions

and network design, you can identify the links whose receive power or transmit power is more

than 3 dB higher or lower than the designed value, and then take appropriate measures in atimely manner.


Fault Symptoms

On an OptiX RTN 600, a 20 km long cross-ocean 1+1 hot standby (HSB) radio link wasinterrupted intermittently, and alarms such as B1_SD, HSB_INDI, MW_LOF, and R_LOF,

were reported and lasted several seconds to dozens of seconds.


Step 1 Checked the ODU receive power that was recorded during the alarm period.


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The difference between the maximum receive power and the minimum receive power was

more than 40 dB, and the minimum receive power was close to or less than the receiver

sensitivity. Therefore, it was inferred that the fault was caused by spatial fading.

Step 2 Checked the network planning design.

The ODU operated at the 8 GHz band, which was less prone to rain fading, and therefore

multipath fading caused intermittent link interruptions. In addition, 1+1 HSB protection does

not well protect radio links against mult ipath fading.

Step 3 Replaced 1+1 HSB protection with 1+1 space diversity (SD) protection.

----End


Routinely check whether the receive power reaches the designed value. If not, it is

recommended that you check the configuration, adjust antennas, or replace ODUs so the

receive power reaches the designed value. Minimize the impact of multipath fading by using one of the following methods,

depending on the actual conditions:

Use low capacity, low-order modulation schemes, and low bandwidths.

Increase the height difference between antennas at both ends providing that

line-of-sight (LOS) is guaranteed.

Add two antennas and configure an SD protection group.

1.6 Loopback


After a loopback is enabled at a point, signals that should be forwarded in normal cases are

routed to the signal source. If services are interrupted, loopbacks can be performed to narrow

down fault areas by checking whether each network section is in good condit ion.

Loopbacks can be software loopbacks or hardware loopbacks. Software loopbacks can beinloops or outloops. For detailed loopback definitions, operation methods, and usage

restrictions, see theMaintenance Guide .


This method allows you to narrow down fault areas by performing loopbacks at different

points and testing services.

Narrowing Down Fault Areas

As shown inFigure 1-3,point A failed to pass a loopback test, and point B passed a loopback

test. Then, the fault existed between point B and point A.


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Figure 1-3Loopbacks helping narrow down fault areas

AB Faulty section

Test result

ERR

OK

ERR

AB

Test meter

Equipment/

Board 1

Equipment/

Board 2

Equipment/

Board 3

Equipment/

Board 4

Equipment/

Board 5

Diagnosing Equipment Interworking Faults

If all sections on the entire network pass loopback tests but the entire network fails in the test,an equipment interworking fault may occur. SeeFigure 1-4.

Figure 1-4Loopbacks for diagnose equipment interworking faults

Test result

ERR

OK

Test meter

OK

Check for an equipment interworking fault.

Test meterEquipment 1 Equipment 2 Equipment 3 Equipment 4 Equipment 5


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Fault Symptoms

Figure 1-5 shows a network, where an E1 tributary between the radio network controller(RNC) and third-party equipment reported an a larm.

Figure 1-5Loopbacks for locating faults

OSN

Third-party

SDH E1 BER tester

7 IFH2

1 PXC

3 PXC

5 IFH2

8

2 SCC

4

6 SD1

7 IFH2

1 PXC

3 PXC

5 IFH2

8

2 SCC

4 PH1

6 SD1

NE1

ODU

ODU

ODU

ODU

NE2

2

RNC

1

A

B


Step 1 Analyzed the service s ignal flow.

The alarmed E1 signal was received from NE2.

Step 2 Checked alarms reported by NE2.

NE2 did not report any hardware a larms or service alarms.

Step 3 Set an inloop at the tributary board (point 1) on NE2, and connected an E1 bit error rate (BER)tester to point A (third-party SDH equipment).

The service had bit errors.

Step 4 Set an outloop at the SD1 board (point 2) on NE1.

The E1 BER tester at point A read no bit error. It was suspected that the radio link between

NE1 and NE2 was faulty.

Step 5 Tested the radio link performance by setting an inloop at the tributary board (point 1) on NE2and connecting an E1 BER tester to point B (OptiX OSN equipment).

The E1 BER tester at point B read no bit error.


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Fault Symptoms

See the following figure. Two sites, site A and site B, were interconnected using 2+0 radiolinks. At each site, ODUs of the same type (with the same sub-band but different working

frequencies) were used. NE B-2 at site B frequently reported services alarms such as R_LOC

and R_LOF.

Figure 1-6Replacement for locating faults

NE A-1

NE A-2

ODU

A-1

ODU

A-2

NE B-1

NE B-2

ODU

B-1

ODU

B-2

Site A Site B

R_LOC/ R_LOF


Step 1 Checked historical performance events and the receive power within the period of alarmreporting.

The receive power was normal.

Step 2 Interchanged the IF cables at site B and checked for alarms for two days.

NE B-2 st ill reported service alarms. Therefore, site B was not faulty, and site A was possibly

faulty.

NE A-1

NE A-2

ODU

A-1

ODU

A-2

NE B-1

NE B-2

ODU

B-1

ODU

B-2

Site A Site B

R_LOC/ R_LOF

Step 3 Restored the IF cable connections at site B, interchanged the IF cables at site A, and checkedfor alarms for two days.

NE B-1 reported service alarms. Therefore, the IF ca ble connecting NE A-2 and ODU A-2

was faulty.


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NE A-1

NE A-2

ODU

A-1

ODU

A-2

NE B-1

NE B-2

ODU

A-1

ODU

A-2

Site A Site B

R_LOC/ R_LOF

Step 4 Replaced the faulty IF cable. The fault was rectified.

----End


If common methods fail to locate the causes of similar problems, you can replace involved

parts one by one.

1.8 Configuration Data Analysis


Incorrect operations or inherent characteristics (for example, at a micro level) of electronic

equipment may corrupt or change equipment's configuration data (for example, NE data and

board data), leading to faults like service interruptions. After locating faults to boards, you cananalyze configuration data to further locate the faults.


This method allows you to query equipment's configuration data, compare the data with

planned data, and analyze the data based on networking topologies and equipment

interconnections.

Radio hop configurations must comply with the following rules:

Each of the following parameters must be consistently set at both ends of a radio hop:

microwave working modes of IF boards (channel spacing, IF bandwidth, and modulation

scheme), number of E1s for Hybrid radio, and IEEE 1588 timeslots. The transmit and receive frequencies of ODUs must be set correctly. To be specific, there

is a T/R spacing between the transmit frequencies of the Tx high and Tx low sites for a

radio hop. That is, for a radio hop, the transmit frequency of the Tx high site must be

equal to the receive frequency of the Tx low site, and the transmit frequency of the Txlow site must be equal to the receive frequency of the Tx high site.


Fault Symptoms

After an OptiX RTN 600 NE was configured, it operated normally. Its services, however,

were interrupted after it restarted after a power failure.


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Step 1 Checked a larms.

The CONIFG_NOSUPPORT alarm indicating an incorrect frequency caused the

RADIO_MUTE alarm.

Step 2 Checked the parameter setting.

The preset Tx frequency was out of the Tx frequency range.

NOTE If an incorrect Tx frequency value is applied to an unmuted ODU, the ODU reports a

CONFIG_NOSUPPORT alarm but remains in the unmute state, so its services are not interrupted. After

the Tx frequency is changed to a correct one, the CONFIG_NOSUPPORT a larm auto matically clears .

However, if an incorrect Tx frequency value is applied to an ODU after the ODU is reset or powered off

or the NE is reset, the ODU remains in the mute s tate and so its services cannot be restored.

Step 3 Changed the Tx frequency to a correct value based on the network planning information.

The fault was rectified.

----End


If services are interrupted due to incorrect operations, check whether the configuration data iscorrect. In addition, analyzing alarms and their parameters help locate configuration errors.

1.9 Tests Using Instruments and Tools


This method is used to locate equipment interworking faults and to test performance

indicators.


Tools such as multimeters, SDH analyzers, SmartBits, and data service packet sniffers are

used to test equipment on live networks and to check whether faults are caused by equipment

faults or external factors.


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Fault Symptoms

In the network shown in following figure, the NMS set up data communication network(DCN) communication with NE1 and NE2 through the multiprotocol label switching (MPLS)

network. NE1 was connected to the MPLS network using a hub and communicated with the

MPLS network through the Open Shortest Path First (OSPF) protocol. The NMS pinged NE1

successfully but failed to ping NE2. Therefore, NMS could not reach NE2. The routing tableof NE1 indicated that NE1 did not learn routes to upstream NEs. The MPLS network had

multiple radio hops at its edge, but the fault occurred only between NE1 and NE2.

Figure 1-7Fault example

NE1 NE2

MPLS

HUB

NOTE

NE1 and NE2 formed a radio hop.


Step 1 Connected the hub to a PC and used the data service packet sniffer to analyze the OSPFpackets received by NE1.

The designated router (DR) IP addresses in the OSPF packets were xx.xx.xx.1, but the IP

address of the NE that sent the DR packets was xx.xx.xx.2. Therefore, NE1 did not receive

any DD packets sent by the DR elected on the OSPF subnet. As a result, NE1 could not createan adjacency with the DR and could not learn OSPF routes.

Step 2 Sniffed and analyzed OSPF packets at another OptiX RTN NE that was connected to theMPLS network and was operating normally.

The OptiX RTN NE received OSPF packets from the DR. Therefore, an OptiX RTN NE fault

was ruled out.

Step 3 Increased the priority of NE1's gateway (IP address: xx.xx.xx.2) so the gateway became theDR on the subnet.

NE1 learned OSPF routes, and NE2 was reac hable to the NMS.

----End


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This method helps to locate equipment interworking faults or data service faults.

1.10 RMON Performance Analysis


If remote monitoring (RMON) is enabled on the NMS, you can perform Ethernet OAM

functions, loopbacks, and ping tests to locate service interruptions or performancedeterioration.


RMON can be used to transfer network monitoring data between network segments. RMON

achieves the following funct ions:

Storing all the statistics on the agent side and supporting offline manager operations

Storing historical data to facilitate fault diagnosis

Supporting error detection and reporting

Supporting multiple manager sites

The OptiX RTN equipment achieves RMON using the following management groups:

Ethernet statistics group

The Ethernet statistics group queries real-time Ethernet port performance statistics of.

Ethernet history groupThe Ethernet history group stores historical Ethernet performance statistics so users can

obtain Ethernet performance of a specific Ethernet port within a historical period. The

Ethernet history group supports the same items as the Ethernet statistics group.

Ethernet history control group

The Ethernet history control group specifies how to obtain historical Ethernet port

performance data.

Ethernet alarm group

The Ethernet alarm group reports an alarm if the value of a monitored item crosses the

preset threshold.

RMON covers the following statistical items:

Number of transmitted packets

Number of transmitted bytes

Number of rece ived packets

Number of rece ived bytes

Number of each type of bad packets

Number of discarded packets


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Fault Symptoms

Figure 1-8 shows a mobile network, where OptiX RTN 600 V100R003s provided backhaultransmission. Packet loss occurred when BTS1 at site 1 and BTS2 at site 2 were pinged from

the RNC, but did not occur when BTS3 at site 3 was pinged.

Figure 1-8Network example for RMON performance analysis

1-001 2-001 2-002 3-001 3-002 4-001

Site 1 Site 2 Site 3

RNC

BTS1 BTS2 BTS3


Step 1 Analyzed the RMON data of NE 3-002 to check whether packet loss was caused byinsufficient radio bandwidth between site 2 and site 3.

The maximum traffic volume of NE 3-001 already reached its maximum air interface

bandwidth (25 Mbit/s). Therefore, packet loss was caused by congestion. For details, see the

following f igure.

Step 2 Changed the air interface capacity of NE 3-001 as required.

Step 3 Performed a ping test.

No packet was lost.


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----End


RMON shows data traffic and air interface bandwidth usage graphically.

1.11 Network Planning Analysis


Network planning is crucial to radio link performance. To address availability issues not

caused by equipment faults, such as bit errors on radio links and frequent interruptions of

radio links, check whether correct methods are used during network planning or whethernetwork planning is based on actua l link conditions.

Based on terrains and rain falling of areas that radio links cover, network planning generally

determines operating frequencies, T/R spacing, transmit power, antenna heights, and

protection/diversity modes. Based on the preceding information, radio link indicators such asnormal receive power, fading margin, and system availability can be obtained.


The following items are often checked:

Availability: Check whether actual link availability meets customers' requirements. Forrain zones (zones L, M, N, P, and Q specified by ITU-T), it is recommended that you use

low frequency bands and polarization direction V. For a radio link subject to severe

multipath fading, it is recommended that you increase the height difference between theantennas at both ends or use 1+1 SD protection as long as LOS is guaranteed.

Multipath fading prediction methods. Generally, the following methods are available:

ITU-R-P.530-7/8 method: It is globally applicable.


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ITU-R-P.530-9 method: It is applicable to areas with high reflection gradients, for

example, the Middle East, the Mediterranean sea, and West Africa. It works with the

ITU-R-P.530-7/8 method. During the prediction, a low availability is used as the

calculation result.

KQ factor method: It is applicable to China (seldom used).

Vigants-Barnett method: It is applicable to North America.

Rain fading prediction methods. Generally, the following methods are available:

ITU-7: It is globally applicable.

R.K. Crane: It is applicable to North America.

For a link covering several rain zones, it is recommended that you select the zonewith the heaviest rainfall for calculation.


Fault SymptomsA radio link frequently but intermittently reported MW_RDI, R_LOC, and RPS_INDI alarms,

and HSB switchovers were triggered.

Table 1-3Link information

Protection 1+1 HSB

IF board IF1B boards

IF mode IF mode 7 (28M/128QAM/STM-1)

ODU type SPA ODUs operating at the 8 GHz frequency band

Receiver sensitivity 70.5 dBm

Transmit power 20 dBm

Receive power 39.5 dBm

Planned availability 99.994%

Predicted annual interrupt ion time 1877 seconds


Step 1 Queried historical receive power values of the radio link.

The receive power decreased to a value close to the receiver sensitivity when an alarm was

reported. Most alarms were reported during the night or in the early morning. When theweather was favorable at noon, the receive power was normal. Therefore, intermittent radio

link interruptions were caused by multipath fading.

Step 2 Checked annual interruption time predicted for the radio link.

The actual annual interruption time was longer than the predicted time of 1877 seconds.

Therefore, the fading margin was insufficient.

Step 3 Checked the network planning methods.


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The ITU-R-P.530-7/8 method was used. The area covered by the radio link was in the Middle

East, and therefore the ITU-R-P.530-9 method should be used.

Step 4 Used the ITU-R-P.530-9 method to predict annual interruption time without changing otherconditions.

The obtained value was about 175833 seconds, which was longer than the value obtained

using the ITU-R-P.530-7/8 method.

Figure 1-9Using the ITU-R-P.530-7/8 method

Figure 1-10Using the ITU-R-P.530-9 method

Step 5 Deleted 1+1 HSB protection settings and configured 1+1 SD protection. The link availability

met service requirements.


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----End


Network planning is crucial to radio link performance. For radio links that are frequentlyinterrupted due to fading, it is recommended that you first check their network planning

information.


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2 Troubleshooting Process and GuideThis chapter describes the general troubleshooting process, fault categories, and how to

diagnose each category of faults.

2.1 Troubleshooting Process Overview

Figure 2-1Troubleshooting flowchart

Start

Record fault symptoms

Diagnose the fault

Is the fault rectified?

Report to Huawei

Work out solutions

together

Is the fault rectified?

Write a troubleshooting

report

End

Rectify external faults

1

34

No

Yes

Yes

No

No

Caused by

external factors?2

Yes


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Table 2-1Remarks about the troubleshooting process

Mark

Explanation

1 When recording fault symptoms, record them as detailed as possible.

Record other important information too, for example, exact time when thefault occurs, operations performed before and after the fault occurs, alarms,

and performance events.

You can collect fault data using the Data Collector (DC) tool that is

integrated with the U2000.

2 External factors include power supply, fibers/cables, environment, and

terminal equipment (such as switches).

3 Find causes of a fault with reference to section1.2 "Common Methods for

Locating Faults", determine the category of the fault with reference to

section2.2 "Fault Categories", and rectify the fault as instructed in the

corresponding section listed below:

2.3 Troubleshooting Radio Links

2.4 Troubleshooting TDM Services

2.5 Troubleshooting Data Services

2.6 Troubleshooting Microwave Protection

2.7 Troubleshooting Clocks

2.8 Troubleshooting DCN Communication

4 Contact Huawei local office or dial Huawei technical service hotline for

problem reporting and technical support.

CAUTION

When handling critical problems such as a service interruption, exercise the followingprecautions:

Restore services as soon as possible.

Analyze fault symptoms, find causes, and then handle faults. If causes are unknown,exercise precautions when you perform operations in case the problems become severer.

If a fault persists, contact Huawei engineers and coordinate with them to handle the fault

promptly. Record the operations performed during fault handling and save the original data related to

the fault.


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2.2 Fault Categories

Table 2-2Fault categories

Fault Category

Typical Symptom

Hardware fault Equipment reports hardware alarms such as BD_STATUS

and HARD_BAD.

Radio link fault Radio links report link-related alarms such as MW_LOF and

RADIO_RSL_LOW, or have bit errors.

Time division

multiplexing (TDM)service fault

Radio links work normally but their carried TDM services are

interrupted or deteriorate.

Data service fault Radio links work normally but their carried data services

have packet loss or are unavailable.

Protection fault Protected radio links or their carried services are faulty, orprotection switching fails (no switchover is performed or

services are unavailable after switching is complete).

Clock fault NEs report clock alarms.

DCN fault NEs fail to be managed by the NMS or do not respond to

commands from the NMS.

2.3 Troubleshooting Radio Links

2.3.1 Radio Link Faults

Fault Causes

Causes of radio link faults are classified into the following categories:

Equipment faults, including indoor unit (IDU) faults, outdoor (ODU) faults, and power

faults

Propagation faults, including fading, interference, and poor LOS

Poor construction quality, including poor antenna/component installation, poor

grounding, and poor waterproofing


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Figure 2-2Causes of radio link faults

Causes of radio

link faults

Propagation faults

Interference Fading Poor LOS

External

interference

Over-reach

interference

Rain fading

Multipath

fading

Reflection

LOS not

achieved

Near-field

blocking

Poor construction

quality

Antenna

installationCables

Antennas not

aligned

Antennasloosened or offset

Poor grounding

Poor

waterproofing

Equipment faults

IDU faults

ODU or outdoor

component faults

Power faultsDamaged cable

components


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Troubleshooting Process

Figure 2-3 illustrates the process for diagnosing a radio link fault.

Figure 2-3Process for diagnosing a radio link fault

Start

Hardware alarms exist?

RSL less than the designed

value if no fading occurs?

RSL greater than the receiver

sensitivity?

Raining when the fault occurs?

The fault occurs regularly?

Rectify equipment faults.

Link interruption time

greater than the

designed value?

Co-channel or adjacent-channel

interference occurs.

Large-delay, multipath reflection occurs.

The link is blocked.

The antennas are offset.

Passive components like hybrid couplers

or flexible waveguides are faulty.

Rain fading

Multipath fading

Terrain reflection

The link reports link-relatedalarms like MW_LOF or bit error

events like UAS/SES?

Handle the fault accordingly.

Yes

No

Yes

No

No

Yes

Yes

No

Yes

No

Yes

No

Check whether the designed value is

appropriate.

Yes

Analyze the configuration data and

replace components that are suspected

to be faulty.

No


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2.3.2 Signal Propagation Faults

For causes of radio link faults, faults caused by active equipment are easily located because

they generally occur with alarms, whereas signal propagation faults (including faults caused

by unaligned antennas), which occur frequently, are difficult to locate.

Table 2-3provides typical symptoms of and solutions to s ignal propagation faults.

Table 2-3Typical symptoms of and solutions to signal propagation faults

FaultType

Typical Symptom

Solution

Multipathfading

The receive power changes greatly andquickly (generally from 10 dB to dozens of

dB within seconds). The changes occur

periodically, especially during the transition

between day and night. A typical symptom of duct-type fading is

that the receive power undergoes substantial

up-fading and down-fading.

Increase the path inclination by adjusting theantenna mount heights at both ends,

therefore increasing height differences

between the antennas at both ends.

Reduce surface reflection. For apparentstrong reflection surfaces, for example, large

areas of water, flat lands, and bold mountain

tops, adjust antennas to move reflection

points out of the strong reflection areas or

mask the reflection by using landforms.

Reduce the path clearance. With LOS

conditions guaranteed, lower antenna mount

heights as much as possible.

Use space diversity or increase the fading

margin. In normal conditions, space diversity

is the most efficient method for decreasing

multipath fading.

Interference A link's receive power is greater than the

receiver sensitivity, but the link is

interrupted or has bit errors.

When no fading occurs, an IF board reports aradio link alarm, especially when

interference is strong.

When interference occurs at the local end

(interference signal power greater than 90dBm), the local receive power is greater than

90 dBm after the peer ODU is muted.

A frequency scanner can detect interference

signal power when being tuned to theoperating band of an ODU.

Plan frequencies or polarization directions

properly. In theory, a large spacing between

the operating frequency of target signals and

the operating frequency of interferencesignals reduces interference. Meanwhile,

note issues such as frequency resources and

network-wide planning.

Plan Tx high and Tx low sites properly. Ifmultiple ODUs provide multiple microwave

directions at a site, plan the site as a Tx high

site or Tx low site for all microwavedirections, if possible.

Plan microwave routes properly. Generally,

adopt Z-shaped radio link distribution to

prevent over-reach interference.


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Fault

Type

Typical Symptom

Solution

Rain fading When it rains, a link may be interrupted or

deteriorate.

Increase link fading margin, use low frequency

bands, or use vertical polarization.

Increase link fading margin for rain zones L,

M, N, P, and Q.

Rain fading impairs radio links that operate

at high frequency bands, especially

frequency bands higher than 18 GHz. Radio

links operating at frequency bands lowerthan 10 GHz are not affected. If rain fading

is severe, change radio links' operating

frequency bands, if necessary.

Rain fading in horizontal polarization isseverer than that in vertical polarization.

Poor LOS The receive power is always lower than the

designed power.

If radio links or antennas are blocked, adjust

antenna mount heights or positions to bypass

obstacles.

Adjust deviated antennas.

2.4 Troubleshooting TDM Services

Fault Symptoms

TDM services are interrupted or have bit errors.


No.

Possible Cause

Handling Procedure

Cause 1 The hardware is faulty. Analyze alarms and perform loopbacks to check whether board

hardware is faulty. If a board is faulty, replace the board.

Cause 2 A radio link is faulty. On the NMS, find the occurrence period of the fault and check whether

any service alarm is generated on the radio link. If a radio link alarm isgenerated, first rectify radio link faults.

Cause 3 Services are incorrectly

configured.

Check whether anMW_CFG_MISMATCH alarm is generated on the

link. Verify that the number of E1s is the same at both ends of the link.

Cause 4 The temperature of a

board is very high.

On the NMS, query the temperatures of components setting up the

faulty link, and check whether any temperature alarm is generated. If

the ODU temperature is very high, take temperature control measures,for example, installing a sunshade. If the IDU temperature is very high,

verify that temperature control devices, for example, air conditioners,

work normally, and verify that the exhaust vents of the IDU are covered

or obstructed.
http://localhost:7890/pages/31184685/01/31184685/01/resources/alm/topic/mw_cfg_mismatch.htmlhttp://localhost:7890/pages/31184685/01/31184685/01/resources/alm/topic/mw_cfg_mismatch.html


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No.

Possible Cause

Handling Procedure

Cause 5 Power supply voltage

fluctuates, the grounding

is improper, or externalinterference exists.

Check whether the voltage of the external input power supply fluctuates

or whether the equipment is grounded improperly.

2.5 Troubleshooting Data ServicesThis section describes how to diagnose data service faults with different symptoms and

affected scopes.

2.5.1 Services at All Base Stations on an Entire Network or in anArea Are Interrupted

Fault Symptoms

On a network, services at all base stations, which are converged at level 1 or level 2

convergence nodes and then transmitted to base station controllers (BSCs)/RNCs, are

interrupted. To be specific, all voice services, Internet access services, and video services areinterrupted.

Cause Analysis

If services at all base stations on an entire network or in an area are interrupted, faultsprobably occur at the convergence nodes that are interconnected with BSCs/RNCs. Therefore,

check for the following faults at convergence nodes:

Board hardware fa ult

Port fault

Configuration error

Equipment interconnection fault

If this type of faults occurs, contact the maintenance personnel for the interconnected

equipment.

Fault Locating Measures

NOTE

Before locating faults, collect data o f all NEs that are poss ibly faulty, if poss ible.

Step 1 Rule out hardware faults and radio link faults with reference to section2.2 "Fault Categories"and 2.3 "Troubleshooting Radio Links."

Step 2 Check whether upstream convergence ports at the convergence nodes report equipmentalarms.

If Then

These ports report any of the Clear the alarms as instructed in "Alarms and


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If Then

following e quipment a larms:

ETH_LOS

LASER_MOD_ERR LASER_NOT_FITED

ETH_NO_FLOW

Handling Procedures" in the Maintenance Guide .

These ports do not report

equipment alarms

Go to the next step.

Step 3 Check RMON statistics about upstream convergence ports at the convergence nodes.

If Then

The ports receive data but do nottransmit data

The boards where the ports locate may be faulty. Inthis case, go to the next step.

The ports do not rece ive data The interconnected equipment is faulty. In this case,

rectify the fault by following instructions in chapter3

"Equipment Interworking Guide ".

The ports receive and transmit data Go to the next step.

Step 4 Check the Ethernet bandwidths provided by radio links at the convergence nodes.

If Then

The Ethernet bandwidths providedby radio links are insufficient

Expand capacities of the radio links to increaseEthernet bandwidths.

The Ethernet bandwidths provided

by radio links are suff icient


Step 5 Check service configurations.

1. Check Ethernet service configurations at the convergence nodes.

If Then

No Ethernet service is configured,

or source/sink ports are incorrectlyset

Re-configure Ethernet services and check whether

the services recover. If not, go to the next step.

Ethernet services are configured as

planned



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2. Check attributes of service ports at the convergence nodes.

If Then

Attributes of the service ports are

incorrectly set

Set attributes for the service ports again (including

port enabled/disabled, tag attribute, and defaultVLAN) and check whether the services recover. If

not, go to the next step.


correctly set


3. Check service VLANs at the convergence nodes.

If Then

VLAN settings are inconsistent

with actual services

Re-set VLANs for the services and check whether

the services recover. If not, go to the next step.

VLAN settings are consistent with

actual services


Step 6 Reset the NEs at the convergence nodes.

NOTE

If the fault persists after all the preceding s teps are performed, dial Huawei technical s ervice hotline or

contact Huawei local office.

----End

2.5.2 Services at All Base Stations on an Entire Network or in anArea Experience Packet Loss

Fault Symptoms

Services at all base stations on an entire network or in an area experience packet loss. For

example, all Internet service users experience a low access rate, calls are delayed, pingpackets between BSCs/RNCs and base stations are lost, or art ifacts appear in video services.

Cause Analysis

If services at all base stations on an entire network or in an area experience packet loss, faults

probably occur at convergence nodes (possibly OptiX PTN 1900 or Opt iX RTN 950) that are

interconnected with BSCs/RNCs. Therefore, check for the following faults at the convergencenodes (the possibility of service configuration errors is eliminated because the services are not

interrupted):

Incorrect parameter setting (for example, mismatched working modes) for Ethernet ports

Network cable or fiber fault

Service traffic exceeding preset bandwidth

Member link fault in link aggregation groups (LAGs)


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Oversized burst traffic

Broadcast storm

Inappropriate quality of service (QoS) parameter setting


NOTE Before locating faults, collect data o f all NEs that are poss ibly faulty, if poss ible.

Step 1 Check whether the convergence nodes report alarms.

If Then

The convergence nodes report alarmslike ETH_LOS or experience alarm

jitters

Clear the alarms as instructed in "Alarms andHandling Procedures" in theMaintenance Guide .

If the alarms clear, check whether the fault is

rectified. If the alarms persist, go to the next step.

The convergence nodes do not reportan alarm


Step 2 At the convergence nodes, check whether the ports used for interconnection and their peerports at the interconnected equipment are consistently set.

If Then

The ports' working modes are

inconsistent with their peer ports'

working modes

Change their working modes to the same and

check whether the fault is rectified. If not, check

the next item.

The ports' physical states aredifferent from the settings

Verify fiber connections or network cableconnections at the ports. Then, enable the ports

again and check whether the fault is rectified. If

not, check the next item.

The ports' maximum transmissionunit (MTU) settings are different

from actual packet lengths

Change the value of the MTU parameter to 9600bytes and check whether the fault is rectified. If

not, check the next item.

The ports are physically normal Go to the next step.


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Cause Analysis

If services at some base stations are interrupted, certain equipment on the transmission link is

faulty. To diagnose the fault, check service continuity on the link and R MON counts of

service ports, determine the fault scope, and check for the following faults at those possibly

faulty nodes:

Board hardware fault

Boards not installed

Abnormal physical ports (used for interconnection)

Service configuration error


NOTE

Before locating faults, collect data of all NEs that are possibly faulty, if poss ible.

Step 1 Check service continuity on each branch of the faulty link to determine the fault scope.

If Then

The services from base stations

or OptiX RTN NEs to an NE on

the faulty link are available, but

the services from the faulty linkto the NE are interrupted

The NE or its next-hop NE on the faulty link is faulty.

In this case, go to the next step.

An NE on the faulty link receives

data but does not transmit data,

or transmits data but does notreceive data

If an NE on the faulty link transmits data but does not

receive data, check the traffic counts of its next-hop

NE. Repeat this operation until you locate the NE thatdoes not transmit data. The located NE is considered a

faulty NE. Then, go to the next step.

Step 2 Check whether the faulty NE reports a larms.

If Then

The NE reports alarms Clear the alarms as instructed in "Alarms and Handling

Procedures" in theMaintenance Guide . If the alarms

clear, check whether the fault is rectified. If not, go tothe next step.

The NE does not report an alarm Go to the next step.


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Step 3 At the faulty NE, check whether the port used for interconnection and its peer port at theinterconnected equipment are consistently set.

If Then

The port's working mode isinconsistent with its peer port's

working mode

Change the working mode to the same and checkwhether the fault is rectified. If not, check the next

item.

The port's physical state is

different from the setting

Verify fiber connection or network cable connection at

the port. Then, enable the port again and check

whether the fault is rectified. If not, check the next

item.

The port's MTU setting is

different from the actual packet

length

Change the value of the MTU parameter to 9216 bytes

and check whether the fault is rectified. If not, go to

the next step.

The port is physically normal Go to the next step.

Step 4 Check service configurations at the faulty NE.

1. Check whether services are correctly configured.

If Then

The services are not configuredor are incorrectly configured

Re-configure the services and check whether theservices recover. If not, go to the next step.

The services are correctly

configured


2. Check attributes of the service ports.

If Then


incorrectly set

Set attributes for the service ports again (including port

enabled/disabled, tag attribute, Layer 2/Layer 3

attribute, and default VLAN) and check whether the

services recover. If not, go to the next step.


correctly set


3. Check the service VLAN. If the service VLAN is incorrectly set, re-set it.

NOTE

If the fault persists after all the preceding s teps are performed, dial Huawei technical service ho tline or


----End


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2.5.4 Services at Some Base Stations in an Area Experience PacketLoss

Fault SymptomsServices at some base stations in an area experience packet loss. For example, some users

experience a low Internet access rate, calls are delayed, some ping packets between a BSCand its subordinate base stations are lost, or artifacts appear in video services.

Cause Analysis

If services at some base stations experience packet loss, certain equipment on the transmission

link is faulty. To diagnose the fault, check service continuity on the link and RMON counts of

service ports, determine the fault scope, and check for the following faults at those possibly

faulty nodes:

Abnormal physical ports (used for interconnection)

Service traffic exceeding preset bandwidth

Oversized burst traffic

Broadcast storm

Inappropriate QoS parameter setting


NOTE

Before locating faults, collect data o f all NEs that are poss ibly faulty, if poss ible.

Step 1 Check RMON counts of ports on the faulty link, and determine the fault scope by comparingtraffic volumes at involved NEs.

If Then

The volume of traffic received byan NE is greater than the volume

of traffic transmitted by the NE

Consider the NE as a faulty NE and go to the nextstep.

The volume of traffic received byan NE is equal to the volume of

traffic transmitted by the NE, but

both volumes are too low

Check the traffic volume at the next-hop NE. Repeatthis operation until you locate the NE whose volume

of received traffic is largely different from its volume

of transmitted traffic. The located NE is considered a

faulty NE. Then, go to the next step.


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Step 2 Check whether the faulty NE reports a larms.

If Then

The NE reports alarms like

ETH_LOS or experiences alarmjitters

Clear the alarms as instructed in "Alarms and

Handling Procedures" in theMaintenance Guide . Ifthe alarms clear, check whether the fault is rectified.

If not, go to the next step.

The NE does not report an alarm Go to the next step.

Step 3 At the faulty NE, check whether the port used for interconnection and its peer port at theinterconnected equipment are consistently set.

If Then

The port's working mode isinconsistent with its peer port's

working mode

Change the working mode to the same and checkwhether the fault is rectified. If not, check the next

item.

The port's physical state isdifferent from the setting

Verify fiber connection or network cable connectionat the port. Then, enable the port again and check

whether the fault is rectified. If not, check the next

item.

The port's MTU setting is differentfrom the actual packet length

Change the value of the MTU parameter to 9600bytes and check whether the fault is rect ified. If not,

check the next item.

The port is physically normal Go to the next step.

Step 4 Check RMON counts of each port on the faulty NE.

If Then

The total volume of traffic

converged to an upstream service

port exceeds the maximumbandwidth configured for the port

Split the traffic or increase the maximum bandwidth

configured for the port. Then check whether the fault

is rectif ied. If not, check the next item.

The burst traffic volume at anupstream service port exceeds the

maximum bandwidth configuredfor the port

Enable traffic shaping for the port, and check whetherthe fault is rectified. If not, check the next item.

The traffic volume at the faulty

NE is normal



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Step 5 Check whether QoS settings are appropriate if QoS policies are configured for the faulty NE.

If Then

The rates preset for QoS control

are lower than actual boundbandwidths

Modify QoS settings.

NOTE If the fault persists after all the preceding s teps are performed, dial Huawei technical s ervice hotline or


----End

2.6 Troubleshooting Microwave Protection

2.6.1 Switchover Failure or Delay in Microwave 1+1 Protection

Fault Symptoms

A switchover in microwave 1+1 protection, triggered by a radio link fault or an equipment

fault, fails or is delayed.


No.

Possible Cause

Handling Procedure

Cause 1 The microwave 1+1 protection group is in theforced or lockout switching state, causing a

switchover fa ilure.

Check the current switching state andswitching records of the microwave 1+1

protection group.

Cause 2 In the microwave 1+1 protection group, both the

main and standby links are interrupted or both the

main and standby units are faulty, resulting in a

switchover fa ilure.

Check the alarms reported by boards in the

microwave 1+1 protection group, and the

current switching state of the microwave 1+1

protection group.

Cause 3 The NE is being reset or a switchover between the

main and standby system control boards just

happens, resulting in a switchover failure or adelayed switchover.

Check the alarms reported by the NE,

switchover records of the main and standby

system control boards (OptiX RTN 950/980NEs support main and standby system control

boards), and the current switching state of the

microwave 1+1 protection group.

Cause 4 An RDI-caused switchover is triggered

immediately after a switchover is complete. As the

RDI-caused switchover needs to wait for theexpiration of the wait-to-restore (WTR) timer (in

revertive mode, the waiting time is the preset WTR

time; in non-revertive mode, the waiting time is

300s), the switchover is delayed.

Check the alarms reported by the NE, and

parameter settings, current switching state,

and switching records of the microwave 1+1protection group.


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No.

Possible Cause

Handling Procedure

Cause 5 In OptiX RTN 600 V100R005/OptiX RTN 900

V100R002C02 and later versions, anti-jitter is

provided for switchovers triggered by RDIs andservice alarms, to prevent repeated microwave 1+1

protection switchovers ca used by deep and fast

fading. As a result, some switchovers are delayed.

Check the alarms reported by the NE, and the

current switching state and switching records

of the microwave 1+1 protection group.

Cause 6 The NE is incorrectly configured or installed, for

example, IFH2 and EMS6 boards on OptiX RTN

620 NEs are incorrectly connected.

Check the NE configuration and installation

according to the microwave 1+1 configuration

standards.

2.6.2 Failure to Switch to the Main Unit in Microwave 1+1

ProtectionFault Symptoms

A microwave 1+1 protection group fails to switch services back to its main unit although its

main link or unit recovers.


No.

Possible Cause

Handling Procedure

Cause 1 The microwave 1+1 protection group works in

non-revertive mode.

Check whether the revertive mode is enabled

for the microwave 1+1 protection group. Ifnot, enable it.

Cause 2 The current switching state of the microwave 1+1

protection group is RDI, so an automatic revertive

switchover cannot take place.

Check whether the current switching state of

the microwave 1+1 protection group is RDI.

If yes, manually clear the RDI state.

Cause 3 When the microwave 1+1 protection group is in

the WTR state, the microwave 1+1 protocol

detects that the main unit is faulty. As a result,revertive switchover to the main unit fails.

Check whether boards in the microwave 1+1

protection group report hardware alarms. If

yes, handle the alarms.

2.6.3 Switchover Failure or Delay in SNCP Protection

Fault Symptoms

After the working channel of a subnetwork connection protection (SNCP) protection groupbecomes faulty, an SNCP switchover fa ils or is delayed.


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No.

Possible Cause

Handling Procedure

Cause 1 The SNCP protection group is in the forced or

lockout switching state, causing a switchoverfailure.

Check the current switching state and

switching records of the SNCP protectiongroup.

Cause 2 Both the working and protection channels in the

SNCP protection group are unavailable, resultingin a switchover failure.

Check the alarms reported by boards in the

SNCP protection group, and the currentswitching state of the SNCP protection group.

Cause 3 The NE is being reset or a switchover between themain and standby system control boards just

happens, resulting in a switchover failure or a

delayed switchover.

Check the alarms reported by the NE, therecords of switchovers between the main and

standby system control boards, and the current

switching state of the SNCP protection group.

Cause 4 On an SNCP ring formed by NEs using both SDH

and Hybrid boards, some NEs use the NE softwareearlier than OptiX RTN 600 V10R005 or OptiX

RTN 900 V100R002C02, or E1_AIS insertion isdisabled for some NEs.

Find the NEs whose NE software versions are

earlier than OptiX RTN 600 V10R005 orOptiX RTN 900 V100R002C02, and the NEs

for which E1_AIS insertion is disabled.

2.7 Troubleshooting Clocks

2.7.1 Analyzing Clock Faults

Fault Symptoms

Fault

Symptom

Alarm

Impact on System

Bit errors

occur in

services.

CLK_NO_TRACE_MODE or EXT_SYNC_LOS

EXT_TIME_LOC

HARD_BAD or SYN_BAD

LTI

S1_SYN_CHANGE

SYNC_C_LOS

If a clock source is lost or its

quality deteriorates, the quality of

services tracing the clock sourceis affected. As a result, pointer

justifications occur and the bit

error rate increases.


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Possible Causes

Possible causes of clock faults are as follows:

A clock source in the system clock source priority list is lost.

All external clock sources of an NE are lost. As a result, the NE's clock enters anabnormal state.

In synchronization status message (SSM) mode, clock sources are switched so the clocksource that an NE traces is switched.

The clock source that an NE traces deteriorates.

The clock source that an external clock port traces is lost.

The system clock does not work in locked mode.

The clock source that an external time port traces is lost.

2.7.2 Handling Common Clock Alarms

The OptiX RTN equipment provides various clock alarms to help locate clock faults. When a

clock system becomes faulty, rectify the fault based on reported alarms.

EXT_SYNC_LOS

No.

Possible Cause

Handling Procedure

Cause 1 The clock input mode (2 Mbit/s

or 2 MHz) configured for an

external clock source is

different from the actual clockinput mode.

On the NMS, check whether the clock input mode configured for

the external clock source is the same as the actual clock input

mode.

If not, change the clock input mode for the external clock source.

Then, check whether the a larm clears.

Cause 2 A system control, switching,and timing board is faulty.

On the

Date post:	02-Jun-2018
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